The present invention relates to a video recording and reproducing apparatus, and a method of reproducing the video, and more specifically to a video recording and reproducing apparatus which is suitably used for recording and reproduction of an MPEG transport stream, and a method of reproducing the video in the apparatus.
In recent years, conventional analogue broadcasting is being shifted to digital broadcasting in the field of television broadcasting service.
The digital broadcasting utilizes picture compression technologies that picture data is transmitted after being compressed, and, as a de fact standard of the picture compression technologies related to digital broadcasting, an MPEG 2 system has been widely prevalent.
With the digital television broadcasting using the MPEG standard, picture data and voice data (AV data) are encoded for processing. The AV data thus encoded is then transmitted to TV sets from a broadcasting station in the form of a transport stream which is time-division multiplexed in comparatively short transmission units (packets).
The transport stream received by a TV set is decoded by a decoder and is then output to a display screen/voice output apparatus as AV data.
The transport stream thus received is temporarily recorded on a recording apparatus such as an HDD (hard disk drive), which also allows reproduction and viewing as required by a viewer. At this time, a user can use special reproduction functions during reproduction, such as fast-forwarding reproduction, rewinding reproduction and jumping reproduction.
Meanwhile, with the MPEG standard, when encoding a picture, it is possible not only to directly encode picture data of all frames, but also to refer to data of neighboring frames that are already encoded and encode only difference from the data. In general, since, in the case of a motion picture, neighboring frames correlate highly each other, it is expected that amount of information after encoding can be significantly reduced by encoding only difference from the neighboring frames.
According to the MPEG standard, pictures are classified into three picture types: an Intra (I) picture, a Predictive (P) picture, and a Bidirectionally predictive (B) picture.
The I-picture is a frame that executes encoding by maintaining independence among Group of Pictures (GOP) without referencing to data of other pictures. On the other hand, the P-picture is a picture that executes encoding by referring to past I-pictures or P-pictures, and the B-picture is a picture that executes encoding by referring to past and future I-pictures or P-pictures. As a result, encoding efficiency becomes higher in the order of I, P and B, which means the I-picture has the lowest encoding efficiency. However, the I-picture has an advantage that pictures can be independently decoded.
Therefore, for conducting special reproduction such as fast forwarding, a picture is reproduced by picking out I-picture only. JP-A-2005-197839 discloses a method for executing special reproduction of a transport stream by storing and reading position information of an I-picture on and from a recording medium such as an HDD.
The related art described above refers to a method that, for executing special reproduction of an MPEG motion picture, position information of an I-picture is stored in a recording medium in advance and is then utilized.
However, in the above-stated related art, it is necessary to have data searched in advance to execute the special reproduction. In addition, the recording medium requires an area for storing position information of an I-picture.
Further, in TV program data that was recorded by another apparatus on a detachable recording medium such as a portable HDD, there is a possibility that I-picture information is not recorded. However, in the above-stated related art, special reproduction of such TV program data that does not contain position information of I-picture had not been taken into consideration.